SMB3 Unix extensions

Tom Talpey ttalpey at
Fri Apr 28 19:34:47 UTC 2017

> -----Original Message-----
> From: samba-technical [mailto:samba-technical-bounces at] On
> Behalf Of Jeremy Allison via samba-technical
> Sent: Wednesday, April 19, 2017 1:03 PM
> To: Steve French <smfrench at>
> Cc: Stefan Metzmacher <metze at>; Pavel Shilovsky
> <pavel.shilovsky at>; samba-technical <samba-
> technical at>
> Subject: Re: SMB3 Unix extensions
> On Tue, Apr 18, 2017 at 10:16:26AM -0500, Steve French wrote:
> > And we do have the slides from SDC.
> >
> > We did reach some conclusions -
> > 1) open with posix create context on root of share will allow us to
> > determined if the server understands posix (so we don't try to send
> > the posix create context on subsequent opens and have it ignored)
> > 2) the capability flags to be returned were discussed at SDC and were
> > pretty simple
> > 3) most features can be done without adding info levels (just with the
> > create context)
> > 4) a new info level (e.g. for fsinfo) was discussed but lower priority
> > and a number was not reserved for new info levels
> > 5) need some info back from Microsoft on opinions about inferring mode
> > from the ACL and also about the 'nfs symlink' (assuming that the other
> > form of symlink reparse point is admin only) vs. simulated symlinks
> > (ala MF symlinks that Apple uses e.g.)
> I've been doing a lot of thinking about SMB2-UNIX-symlinks since the recent
> CVE security patch.
> As SambaXP is only 2 weeks away can we get all the stakeholders in a room
> together and try and hash out a plan to deal with the issues with creating UNIX
> symlinks/reparse points ?

Gladly, and my slides say so too! I'm covering in-progress and open items as part of my SambaXP talk. 😊

We've got some notes from conversations at the last Plugfest, and some other material that I'll try to pull together. We'll have time at SambaXP to organize, and hopefully some of you are coming to the Redmond event we're hosting in June? That will give some other Microsoft folks a chance to join in person, since not everyone will be in Göttingen.


> Some of this is Samba specific, which isn't useful to external implementors, but
> if possible I'd really like to re-use the existing SMB2+ reparse mechanisms to
> implement UNIX extension sylinks.

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